Image output apparatuses which generate and output video pictures and images, including game consoles and digital versatile disc players (DVD players), are used as they are with various types of display units such as plasma display televisions, liquid crystal display televisions, CRT televisions, or liquid crystal display monitors.
These display units do not necessarily have display screens with a standardized aspect ratio. Display screens with aspect ratios of 4:3 and 16:9 are commonly in use at present.
When displaying video contents such as a movie or a game on these display screens with different aspect ratios, DVD players and game consoles display images corresponding to the aspect ratios of the respective display units by using a letterbox method, a pan-and-scan method, or a squeeze method. These methods have sometimes caused problems as display screens being only partly used, images that are supposed to be displayed being in part not displayed, or images being distorted.
To solve these problems, it might be possible to generate and output different pictures or images depending on the aspect ratios of the respective display screens. For example, when a game console outputs three-dimensional graphic images, the three-dimensional models may be created in a world coordinate system that is provided for a volume greater than possible view volumes, so that images and video pictures to be displayed are generated by modifying a clipping area according to the aspect ratio of the display screen.
In this case, it is possible to output distortion-free images on the entire display screen simply by modifying the view clip and without changing the three-dimensional modeling processing. Nevertheless, in the case of a car racing game, for example, there may arise the problem that adjacent cars appear on a display screen with one aspect ratio while they disappear from a display screen with a different aspect ratio. Moreover, in games where players can change character positions and views freely, objects that must not be displayed on display screens or that should be hidden from the game players may inadvertently appear in some cases.
Unlike movies and other such contents, games have the property that scenes to be displayed on display screens vary minute by minute with player instructions. When programming games, it is therefore unrealistic, in view of the necessary effort to predict every player instruction and perform tests and debugs with display screens with different aspect ratios.